الفهرس 
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Abstract
The present study was carried out at the New Valley Agricultural Research Station, Agricultural Research Center, during the three successive growing seasons of 2003/2004, 2004/2005 and 2005/2006. The objective of this study was, to estimate the efficiency of three breeding methods, i. e., pedigree, modified bulk and single seed descent methods in the two bread wheat populations. The final evaluation was done during 2005/2006 season in F5 generation. The grains of selected plants were sown in two separated experiments by randomized complete blocks design with four replications.
The materials used in this study were as follows:-
1- Population I : Sids-7 x Sids-1.
2- Population II : Sahel-1 x Giza-164.
The breeding materials used in this study were 30 families F5 from each population divided on methods by equal, original parents and a check cultivar (Giza-168).
The studied traits were, plant height [PH], number of days to heading [DH], number of days to maturity [DM], number of spikes per plant [S/P], spike length [SL], number of kernels per spike [K/S], 1000-kernel weight [KW], biological yield per plant [BY/P] and grain yield per plant [GY/P].
The efficiency of the breeding methods was evaluated on the basis of the following parameters; mean performance, actual response to selection, phenotypic and genotypic variances, phenotypic and genotypic coefficient of variability and broad sense heritability.
The results obtained could be summarized as follows :
1- Response to selection and genetic parameters:
1-1- Plant height [PH]:-
The differences among the genotypes, the breeding methods and the families within breeding methods were significant in the two populations. Pedigree and single seed descent methods had the higher values of actual response to selection in the two populations. Moreover, pedigree and modified bulk methods possessed the higher values of phenotypic variance in two populations. Meanwhile, modified bulk method recorded the higher values of genotypic variance in the two populations. Furthermore, pedigree and modified bulk methods achieved the higher values of phenotypic coefficient of variability in the two populations. Meanwhile, modified bulk method exhibited the higher values of genotypic coefficient of variability in the two populations. While, modified bulk and single seed descent methods possessed the higher values of broad sense heritability in two populations. These results refer to modified bulk and single seed descent methods are more effective in improving plant height.
1-2- Number of days to heading [DH]:-
The differences among the genotypes, the breeding methods and the families within breeding methods were significant in the two populations. Whereas, pedigree, modified bulk and single seed descent methods recorded the higher values of actual response to selection in the two populations. Meanwhile, pedigree method exhibited the higher values of phenotypic and genotypic coefficients of variability in the two populations. Furthermore, pedigree and single seed descent methods possessed the higher values of broad sense heritability in the two populations. These results clear that pedigree and single seed descent methods are more effective in improving earliness.
1-3- Number of days to maturity [DM]:-
Significant differences were observed among the genotypes, the breeding methods and the families within breeding methods in the two populations. The highest values of the actual response was obtained from applied pedigree, modified bulk and single seed descent methods. The highest values of phenotypic and genotypic variances were obtained from applied pedigree and single seed descent methods. Moreover, pedigree and single seed descent methods recorded the highest values of phenotypic and genotypic coefficients of variability and broad sense heritability. These results refer to pedigree and single seed descent methods are more effective in improving earliness.
1-4- Number of spikes per plant [S/P]:-
Results of number of spikes per plant showed significant differences among the genotypes, the breeding methods and the families within breeding methods in the two populations except, the breeding methods and the families within modified bulk method in the population I. The highest values of actual response to selection for number of spikes per plant were obtained with applied single seed descent method in the two populations. Applied of pedigree and modified bulk selection methods had the highest values of phenotypic and genotypic variances in the two populations. Whereas, the phenotypic and genotypic coefficient of variability have the highest values with applied pedigree and modified bulk selection methods in the two populations. Meanwhile, pedigree method recorded the highest values of broad sense heritability in the two populations. These results refer to pedigree and modified bulk methods are more effective in improving tillers.
1-5- Spike length [SL]:-
The differences among the different genotypes, the breeding methods and the families within breeding methods were significant in the two populations except, the families within single seed descent method in the population I and the breeding methods in the population II. Pedigree method recorded the highest values of the actual response to selection in the two populations. Furthermore, pedigree and modified bulk methods had the highest values of phenotypic and genotypic variances in the two populations. Meanwhile, modified bulk method had the highest values of the phenotypic and genotypic coefficients of variability and broad sense heritability in the two populations. These results show that pedigree and modified bulk methods are more effective in improving long spike.
1-6- Number of kernels per spike [K/S]:-
Results of number of kernels per spike showed significant differences among the genotypes, the breeding methods and the families within breeding methods in the two populations. Results revealed that pedigree and single seed descent methods had the highest values for actual response to selection in the two populations. On the other hand, pedigree and modified bulk methods possessed the highest values of phenotypic and genotypic variances, phenotypic and genotypic coefficients of variability and broad sense heritability in the two populations. These results refer to pedigree and modified bulk methods are more effective in improving kernels.
1-7- 1000-kernel weight [KW]:-
Analysis of variance revealed significant differences among the genotypes, the breeding methods and the families within breeding methods in the two populations. Pedigree and modified bulk methods had the highest values of the actual response to selection in the two populations. Meanwhile, pedigree and single seed descent methods recorded the highest values of phenotypic and genotypic variances, phenotypic and genotypic coefficients of variability in the two populations. Moreover, modified bulk and single seed descent methods possessed the highest values of broad sense heritability in any population. These results reveal that pedigree, modified bulk and single seed descent methods are effective in improving kernel weight.
1-8- Biological yield per plant [BY/P]:-
Significant differences were reported among the genotypes, the breeding methods and the families within breeding methods in the two populations. Results revealed that modified bulk and single seed descent methods had the highest values for actual response to selection in the two populations. On the other hand, single seed descent method possessed the highest values of phenotypic and genotypic variances in the two populations. Meanwhile, pedigree and single seed descent methods recorded the highest values for phenotypic coefficient of variability in the two populations. On the other hand, single seed descent method had the highest values of genotypic coefficient of variability and broad sense heritability in the two populations. These results conclude that modified bulk and single seed descent methods are more effective in improving biomass yield .
1-9- Grain yield per plant [GY/P]:-
For grain yield per plant, the results indicated the presence of significant differences among the genotypes, the breeding methods and the families within breeding methods in the two populations. Appling single seed descent and modified bulk selection methods gave the highest values for actual response to selection in the two populations. Meanwhile, single seed descent method had the highest values of phenotypic and genotypic variances, phenotypic and genotypic coefficients of variability and broad sense heritability in the two populations. These results accept that single seed descent method is more effective in improving grain yield.
2- Phenotypic and genotypic correlations:
2-1- Population I:-
2-1-1- Correlation in pedigree method:-
Phenotypic and genotypic correlations were significant and positive between plant height and each of days to heading, days to maturity, spikes per plant, spike length, kernels per spike, biological and grain yield per plant. While, phenotypic and genotypic correlations between days to heading and each of days to maturity, spikes per plant, spike length, kernels per spike, biological and grain yield per plant were significant and positive.
Phenotypic and genotypic correlations were significant and positive between days to maturity and each of spikes per plant, spike length, kernels per spike, biological and grain yield per plant. While, phenotypic and genotypic correlations were significant and positive between spikes per plant and each of biological and grain yield per plant.
Phenotypic and genotypic correlations were significant and positive between spike length and each of kernels per spike, biological and grain yield per plant. Whereas, phenotypic and genotypic correlations were significant and positive between kernels per spike and each of biological and grain yield per plant. While, phenotypic and genotypic correlations were significant and negative between 1000-kernel weight and all traits except spikes per plant. Furthermore, phenotypic and genotypic correlations for biological yield per plant with grain yield per plant was significant and positive.
2-1-2- Correlation in modified bulk method:-
Phenotypic and genotypic correlations for plant height and each of days to heading, days to maturity, spike length, kernels per spike, biological and grain yield per plant were significant and positive. While, phenotypic and genotypic correlations for days to heading and each of days to maturity, spikes per plant, spike length, kernels per spike, biological and grain yield per plant were significant and positive.
The values of phenotypic and genotypic correlations for maturity date and each of spikes per plant, spike length, kernels per spike and grain yield per plant were significant and positive. Whereas, insignificant and positive phenotypic and genotypic correlations were found between spikes per plant and each of spike length, kernels per spike, biological and grain yield per plant.
Significant and positive phenotypic and genotypic correlations were recorded between spike length and each of kernels per spike, biological and grain yield per plant. Furthermore, phenotypic and genotypic correlations for kernels per spike and each of biological and grain yield per plant were significant and positive. Moreover, phenotypic and genotypic correlations for 1000-kernel weight and all traits were significant and negative except, plant height. While, biological yield per plant recorded significant and positive phenotypic and genotypic correlations with grain yield per plant.
2-1-3- Correlation in single seed descent method:-
Plant height exhibited significant and positive phenotypic and genotypic correlations with spike length. While, phenotypic and genotypic correlations for days to heading and each of days to maturity and kernels per spike were significant and positive.
The results of phenotypic and genotypic correlations indicated that maturity date was significantly and positively correlated with kernels per spike. Furthermore, phenotypic and genotypic correlations between spikes per plant and each of spike length, biological and grain yield per plant were significant and positive.
The values of phenotypic and genotypic correlations revealed that spike length was significantly and positively correlated and each of kernels per spike, 1000-kernel weight, biological and grain yield per plant. Whereas, phenotypic and genotypic correlations between kernels per spike and each of days to heading, days to maturity and spike length were significant and positive. Moreover, significant and negative phenotypic correlation was found between 1000-kernel weight and each of days to heading and maturity, while, significant and positive genotypic correlation was recorded between 1000-kernel weight and each of biological and grain yield per plant. Furthermore, phenotypic and genotypic correlations between biological yield per plant and grain yield per plant were significant and positive.
2-2- Population II:-
2-2-1- Correlation in pedigree method:-
The values of phenotypic correlation revealed that plant height was significantly and negatively correlated with days to maturity, while, genotypic correlation between plant height and spikes per plant was significant and positive. Whereas, significant and positive phenotypic and genotypic correlations was found between days to heading and each of days to maturity, spike length, kernels per spike, biological and grain yield per plant.
Significant and positive phenotypic and genotypic correlations was recorded between maturity date and days to heading. While, phenotypic correlation between spikes per plant and each of spike length, kernels per spike, 1000-kernel weight, biological and grain yield per plant was insignificant and positive, and, genotypic correlation between spikes per plant and 1000-kernel weight was significant and positive.
Significant and positive phenotypic and genotypic correlations were obtained between spike length and each of kernels per spike, biological and grain yield per plant. Whereas, phenotypic and genotypic correlations were significant and positive between kernels per spike and each of biological and grain yield per plant. Furthermore, significant and negative phenotypic correlation was found between 1000-kernel weight and each of days to heading and kernels per spike, and, genotypic correlation between 1000-kernel weight and spikes per plant was significant and positive. Moreover, phenotypic and genotypic correlations between biological and grain yield per plant were significant and positive.
2-2-2- Correlation in modified bulk method:-
Phenotypic and genotypic correlations for plant height with kernels per spike were significant and negative. While, phenotypic and genotypic correlations for days to heading with days to maturity were significant and positive.
The values of phenotypic and genotypic correlations for maturity date with 1000-kernel weight were significant and positive. Furthermore, phenotypic and genotypic correlations for spikes per plant and each of spike length, biological and grain yield per plant were significant and positive.
Phenotypic and genotypic correlations indicated that spike length was significantly and positively correlated with spikes per plant. Whereas, phenotypic correlation for kernels per spike with plant height was significant and negative, and, genotypic correlation for kernels per spike with days to heading was significant and positive. Moreover, phenotypic and genotypic correlations for 1000-kernel weight with days to maturity were significant and positive. Furthermore, phenotypic and genotypic correlations for biological and grain yield per plant were significant and positive.
2-2-3- Correlation in single seed descent method:-
Significant and positive phenotypic and genotypic correlations were recorded between plant height and each of days to heading, days to maturity, spikes per plant, spike length, kernels per spike, biological and grain yield per plant. While, phenotypic and genotypic correlations for days to heading and each of days to maturity, spike length, kernels per spike, biological and grain yield per plant were significant and positive.
Phenotypic and genotypic correlations revealed that maturity date was significantly and positively correlated with each of spike length, kernels per spike, biological and grain yield per plant. Furthermore, phenotypic and genotypic correlations for spikes per plant with and each of biological and grain yield per plant were significant and positive.
Significant and positive phenotypic and genotypic correlations were obtained between spike length and each of kernels per spike, biological and grain yield per plant. Whereas, phenotypic and genotypic correlations for kernels per spike and each of biological and grain yield per plant were significant and positive. Moreover, the values of phenotypic and genotypic correlations showed that 1000-kernel weight were significantly and negatively correlated with all traits except spikes per plant and grain yield per plant which recorded insignificant correlation. Furthermore, phenotypic and genotypic correlations for biological and grain yield per plant were significant and positive.